This invention relates to compounds which are modulators of the receptor for advanced glycated end products (RAGE) and interaction with its ligands such as advanced glycated end products (AGEs), S100/calgranulin/EN-RAGE, xcex2-amyloid and amphoterin, for the management, treatment, control, or as an adjunct treatment of diseases caused by RAGE.
Incubation of proteins or lipids with aldose sugars results in nonenzymatic glycation and oxidation of amino groups on proteins to form Amadori adducts. Over time, the adducts undergo additional rearrangements, dehydrations, and cross-linking with other proteins to form complexes known as Advanced Glycosylation End Products (AGEs). Factors which promote formation of AGEs included delayed protein turnover (e.g. as in amyloidoses), accumulation of macromolecules having high lysine content, and high blood glucose levels (e.g. as in diabetes) (Hori et al., J. Biol. Chem. 270: 25752-761, (1995)). AGEs have implicated in a variety of disorders including complications associated with diabetes and normal aging.
AGEs display specific and saturable binding to cell surface receptors on endothelial cells of the microvasculature, monocytes and macrophages, smooth muscle cells, mesengial cells, and neurons. The Receptor for Advanced Glycated Endproducts (RAGE) is a member of the immunoglobulin super family of cell surface molecules. The extracellular (N-terminal) domain of RAGE includes three immunoglobulin-type regions, one V (variable) type domain followed by two C-type (constant) domains (Neeper et al., J. Biol. Chem. 267:14998-15004 (1992). A single transmembrane spanning domain and a short, highly charged cytosolic tail follow the extracellular domain. The N-terminal, extracellular domain can be isolated by proteolysis of RAGE to generate soluble RAGE (sRAGE) comprised of the V and C domains.
RAGE is expressed in most tissues, and in particular, is found in cortical neurons during embryogenesis (Hori et al., J. Biol. Chem. 270:25752-761 (1995)). Increased levels of RAGE are also found in aging tissues (Schleicher et al., J. Clin. Invest. 99 (3): 457-468 (1997)), and the diabetic retina, vasculature and kidney (Schmidt et al., Nature Med. 1:1002-1004 (1995)). Activation of RAGE in different tissues and organs leads to a number of pathophysiological consequences. RAGE has been implicated in a variety of conditions including: acute and chronic inflammation (Hofmann et al, Cell 97:889-901 (1999)), the development of diabetic late complications such as increased vascular permeability (Wautier et al., J. Clin. Invest. 97:238-243 (1995)), nephropathy (Teillet et al., J. Am. Soc. Nephrol. 11:1488-1497 (2000)), atherosclerosis (Vlassara et. al., The Finnish Medical Society DUODECIM, Ann. Med. 28:419-426 (1996)), and retinopathy (Hammes et al., Diabetologia 42:603-607 (1999)). RAGE has also been implicated in Alzheimer""s disease (Yan et al., Nature 382: 685-691, (1996)), erectile dysfunction, and in tumor invasion and metastasis (Taguchi et al., Nature 405: 354-357, (2000)).
In addition to AGEs, other compounds can bind to, and modulate RAGE. In normal development, RAGE interacts with amphoterin, a polypeptide which mediates neurite outgrowth in cultured embryonic neurons (Hori et al., 1995). RAGE has also been shown to interact with EN-RAGE, a protein having substantial similarity to calgranulin (Hofmann et al., Cell 97:889-901 (1999)). RAGE has also been shown to interact with xcex2-amyloid (Yan et al., Nature 389:589-595, (1997); Yan et al., Nature 382:685-691 (1996); Yan et al., Proc. Natl.Acad. Sci., 94:5296-5301 (1997)).
Binding of ligands such as AGEs, S100/calgranulin/EN-RAGE, xcex2-amyloid, CML (Nxcex5-Carboxymethyl lysine), and amphoterin to RAGE has been shown to modify expression of a variety of genes. For example, in many cell types interaction between RAGE and its ligands generates oxidative stress, which thereby results in activation of the free radical sensitive transcription factor NF-xcexaB, and the activation of NF-xcexaB regulated genes, such as the cytokines IL-1xcex2, TNF-xcex1, and the like. In addition, several other regulatory pathways, such as those involving p21 ras, MAP kinases, ERK1 and ERK2, have been shown to be activated by binding of AGEs and other ligands to RAGE. In fact, transcription of RAGE itself is regulated at least in part by NF-xcexaB. Thus, an ascending, and often detrimental, spiral is fueled by a positive feedback loop initiated by ligand binding. Antagonizing binding of physiological ligands to RAGE, therefore, is our target for down-regulation of the pathophysiological changes brought about by excessive concentrations of AGEs and other ligands for RAGE.
Thus, there is a need for the development of compounds that antagonize binding of physiological ligands to the RAGE receptor.
This invention provides compounds which are useful as RAGE modulators. In a preferred embodiment, the present invention provides compounds of Formula (I) as depicted below, to methods of their preparation, pharmaceutical compositions comprising the compounds and to their use in treating human or animal disorders. The compounds of the invention are useful as modulators of the interaction of the receptor for advanced glycated end products (RAGE) with its ligands such as advanced glycated end products (AGEs), S100/calgranulin/EN-RAGE, xcex2-amyloid and amphoterin, and thus are useful for the management, treatment, control, and/or as an adjunct treatment of diseases in humans caused by RAGE. Such diseases or disease states include acute and chronic inflammation, the development of diabetic late complications such as increased vascular permeability, nephropathy, atherosclerosis, and retinopathy, the development of Alzheimer""s disease, erectile dysfunction, and tumor invasion and metastasis.
In a first aspect, the present invention provides a compound comprising at least one moiety of the formula 
wherein L1 and L2 are each a hydrocarbon group of from 1 to 6 carbons or a direct bond, and Aryl1 and Aryl2 are aryl, wherein each of Aryl1 and Aryl2 are substituted by at least one lipophilic group. In a preferred embodiment, the lipophilic group is selected from C1-6 alkyl, C1-6 alkoxy, C1-6 alkylaryl, or C1-6 alkoxyaryl. We have found such compounds to be useful in the modulation, preferably in the inhibition of the interaction of RAGE with its physiological ligands, as will be discussed in more detail below.
In a second aspect, the present invention provides compounds of Formula (I): 
wherein
R1 and R2 are independently selected from
a) xe2x80x94H;
b) xe2x80x94C1-6 alkyl;
c) -aryl;
d) xe2x80x94C1-6 alkylaryl;
e) xe2x80x94C(O)xe2x80x94Oxe2x80x94C1-6 alkyl;
f) xe2x80x94C(O)xe2x80x94Oxe2x80x94C1-6 alkylaryl;
g) xe2x80x94C(O)xe2x80x94NHxe2x80x94C1-6 alkyl;
h) xe2x80x94C(O)xe2x80x94NHxe2x80x94C1-6 alkylaryl;
i) xe2x80x94SO2xe2x80x94C1-6 alkyl;
j) xe2x80x94SO2xe2x80x94C1-6 alkylaryl;
k) xe2x80x94SO2-aryl;
l) xe2x80x94SO2xe2x80x94NHxe2x80x94C1-6 alkyl;
m) xe2x80x94SO2xe2x80x94NHxe2x80x94C1-6 alkylaryl;
n) 
o) xe2x80x94C(O)xe2x80x94C1-6 alkyl; and
p) xe2x80x94C(O)xe2x80x94C1-6 alkylaryl;
R3 is selected from
a) xe2x80x94C1-6 alkyl;
b) -aryl; and
c) xe2x80x94C1-6 alkylaryl;
R4 is selected from
a) xe2x80x94C1-6 alkylaryl;
b) xe2x80x94C1-6 alkoxyaryl; and
c) -aryl;
R5 and R6 are independently selected from the group consisting of hydrogen, C1-C6 alkyl, C1-C6 alkylaryl, and aryl; and wherein
the aryl and/or alkyl group(s) in R1, R2, R3, R4, R5, R6, R7, R8, R9, R10, R18, R19, and R20 may be optionally substituted 1-4 times with a substituent group, wherein said substituent group(s) or the term substituted refers to groups selected from the group consisting of:
a) xe2x80x94H;
b) xe2x80x94Yxe2x80x94C1-6 alkyl;
xe2x80x94Y-aryl;
xe2x80x94Yxe2x80x94Cxe2x80x941-6 alkylaryl;
xe2x80x94Yxe2x80x94C1-6-alkyl-NR7R8; and
xe2x80x94Yxe2x80x94C1-6-alkyl-Wxe2x80x94R20;
wherein Y and W are, independently selected from the group consisting of xe2x80x94CH2xe2x80x94, xe2x80x94Oxe2x80x94, xe2x80x94N(H), xe2x80x94Sxe2x80x94, SO2xe2x80x94, xe2x80x94CON(H)xe2x80x94, xe2x80x94NHC(O)xe2x80x94, xe2x80x94NHCON(H)xe2x80x94, xe2x80x94NHSO2xe2x80x94, xe2x80x94SO2N(H)xe2x80x94, xe2x80x94C(O)xe2x80x94Oxe2x80x94, xe2x80x94NHSO2NHxe2x80x94, xe2x80x94Oxe2x80x94COxe2x80x94, 
and
c) halogen, hydroxyl, cyano, carbamoyl, or carboxyl; and
R18 and R19 are independently selected from the group consisting of aryl, C1-C6 alkyl, C1-C6 alkylaryl, C1-C6 alkoxy, and C1-C6 alkoxyaryl;
R20 is selected from the group consisting of aryl, C1-C6 alkyl, and C1-C6 alkylaryl;
R7, R8, R9 and R10 are independently selected from the group consisting of hydrogen, aryl, C1-C6 alkyl, and C1-C6 alkylaryl; and wherein
R7 and R8 may be taken together to form a ring having the formula xe2x80x94(CH2)mxe2x80x94Xxe2x80x94(CH2)nxe2x80x94 bonded to the nitrogen atom to which R7 and R8 are attached, and/or R5 and R6 may, independently, be taken together to form a ring having the formula xe2x80x94(CH2)mxe2x80x94Xxe2x80x94(CH2)nxe2x80x94 bonded to the nitrogen atoms to which R5 and R6 are attached, wherein m and n are, independently, 1, 2, 3, or 4; X is selected from the group consisting of xe2x80x94CH2xe2x80x94, xe2x80x94Oxe2x80x94, xe2x80x94Sxe2x80x94, xe2x80x94S(O2)xe2x80x94, xe2x80x94C(O)xe2x80x94, xe2x80x94CON(H)xe2x80x94, xe2x80x94NHC(O)xe2x80x94, xe2x80x94NHCON(H)xe2x80x94, xe2x80x94NHSO2xe2x80x94, xe2x80x94SO2N(H)xe2x80x94, xe2x80x94C(O)xe2x80x94Oxe2x80x94, xe2x80x94Oxe2x80x94C(O)xe2x80x94, xe2x80x94NHSO2NHxe2x80x94, 
or a pharmaceutically acceptable salt, solvate or prodrug thereof.
In the compounds of Formula (I), the various functional groups represented should be understood to have a point of attachment at the functional group having the hyphen. In other words, in the case of xe2x80x94C1-6 alkylaryl, it should be understood that the point of attachment is the alkyl group; an example would be benzyl. In the case of a group such as xe2x80x94C(O)xe2x80x94NHxe2x80x94C1-6 alkylaryl, the point of attachment is the carbonyl carbon.
In a preferred embodiment of this aspect of the invention, the compounds of Formula (I) include those wherein:
R1 is hydrogen;
R2 is selected from
a) xe2x80x94H;
b) xe2x80x94C1-6 alkyl;
c) xe2x80x94C1-6 alkylaryl;
d) xe2x80x94C(O)xe2x80x94Oxe2x80x94C1-6 alkyl;
e) xe2x80x94C(O)xe2x80x94NHxe2x80x94C1-6 alkyl;
f) xe2x80x94C(O)xe2x80x94NHxe2x80x94C1-6 alkylaryl;
g) xe2x80x94SO2xe2x80x94C1-6 alkyl;
h) xe2x80x94SO2xe2x80x94C1-6 alkylaryl;
i) xe2x80x94SO2xe2x80x94NHxe2x80x94C1-6 alkyl; and
j) 
k) xe2x80x94C(O)xe2x80x94C1-6 alkyl;
l) xe2x80x94C(O)xe2x80x94C1-6 alkylaryl;
R3 is selected from
a) xe2x80x94C1-4 alkylaryl; and
R4 is selected from
a) xe2x80x94C1-6 alkylaryl; and
b) -aryl;
and wherein the aryl group in R1, R2, R3 and R4 is optionally substituted 1-4 times with a substituent group, wherein said substituent group(s) or the term substituted refers to groups selected from the group consisting of:
a) xe2x80x94H;
b) xe2x80x94Yxe2x80x94C1-6 alkyl;
xe2x80x94Y-aryl;
xe2x80x94Yxe2x80x94Cxe2x80x941-6 alkylaryl;
xe2x80x94Yxe2x80x94C1-6-alkyl-NR7R8; and
xe2x80x94Yxe2x80x94C1-6-Wxe2x80x94R20;
wherein Y and W are, independently selected from the group consisting of xe2x80x94CH2xe2x80x94, xe2x80x94Oxe2x80x94, xe2x80x94N(H), xe2x80x94Sxe2x80x94, SO2xe2x80x94, xe2x80x94CON(H)xe2x80x94, xe2x80x94NHC(O)xe2x80x94, xe2x80x94NHCON(H)xe2x80x94, xe2x80x94NHSO2xe2x80x94, xe2x80x94SO2N(H)xe2x80x94, xe2x80x94C(O)xe2x80x94Oxe2x80x94, xe2x80x94NHSO2NHxe2x80x94, xe2x80x94Oxe2x80x94COxe2x80x94, 
and
c) halogen, hydroxyl, carbamoyl, and carboxyl;
R18 and R19 are selected from the group consisting of aryl, C1-C6 alkyl, C1-C6 alkylaryl, C1-C6 alkoxy, and C1-C6 alkoxyaryl;
R20 is selected from the group consisting of aryl, C1-C6 alkyl, or C1-C6 alkylaryl, and wherein
R7 and R8 are selected from the group consisting of hydrogen, aryl, C1-C6 alkyl, or C1-C6 alkylaryl; and wherein
R7 and R8 may be taken together to form a ring having the formula xe2x80x94(CH2)mxe2x80x94Xxe2x80x94(CH2)nxe2x80x94 bonded to the nitrogen atom to which R7 and R8 are attached, and/or R5 and R6 may, independently, be taken together to form a ring having the formula xe2x80x94(CH2)mxe2x80x94Xxe2x80x94(CH2nxe2x80x94 bonded to the nitrogen atoms to which R5 and R6 are attached, wherein m, n, and X are as defined above.
In a further preferred embodiment, the R3 groups above include C1-3 alkylaryl, said aryl optionally substituted by substituted 1-4 times with a substituent group, wherein said substituent group(s) or the term substituted refers to groups selected from the group consisting of:
xe2x80x94Yxe2x80x94C1-6 alkyl;
xe2x80x94Y-aryl;
xe2x80x94Yxe2x80x94Cxe2x80x941-6 alkylaryl;
xe2x80x94Yxe2x80x94C1-6-alkyl-NR7R8; and
xe2x80x94Yxe2x80x94C1-6-alkyl-Wxe2x80x94R20;
wherein Y and W are, independently selected from the group consisting of xe2x80x94CH2xe2x80x94, xe2x80x94Oxe2x80x94, xe2x80x94N(H), xe2x80x94Sxe2x80x94, SO2xe2x80x94, xe2x80x94CON(H)xe2x80x94, xe2x80x94NHC(O)xe2x80x94, xe2x80x94NHCON(H)xe2x80x94, xe2x80x94NHSO2xe2x80x94, xe2x80x94SO2N(H)xe2x80x94, xe2x80x94C(O)xe2x80x94Oxe2x80x94, xe2x80x94NHSO2NHxe2x80x94, xe2x80x94Oxe2x80x94COxe2x80x94, 
A further preferred embodiment is the embodiment referred to above, wherein aryl is phenyl or napthyl, optionally substituted by C1-6 alkyl, C1-6 alkoxy, C1-6 alkylaryl, or C1-6 alkoxyaryl.
Also included within the scope of the invention are the individual enantiomers of the compounds represented by Formula (I) above as well as any wholly or partially racemic mixtures thereof. The present invention also covers the individual enantiomers of the compounds represented by formula above as mixtures with diastereoisomers thereof in which one or more stereocenters are inverted.
Compounds of the present invention which are preferred for their high biological activity are listed by name below in Table 1.
Accordingly, in a further embodiment of the invention, there is provided the above compounds, or the free amine, free acid, solvate, prodrug, or pharmaceutically acceptable salt thereof.
As used herein, the term xe2x80x9calkylxe2x80x9d refers to a straight or branched chain hydrocarbon having the number of specified carbon atoms. Examples of xe2x80x9calkylxe2x80x9d as used herein include, but are not limited to, methyl, n-butyl, n-pentyl, isobutyl, and isopropyl, and the like.
As used herein, the term xe2x80x9calkylenexe2x80x9d refers to a straight or branched chain divalent hydrocarbon radical having from one to ten carbon atoms, optionally substituted with substituents selected from the group consisting of lower alkyl, lower alkoxy, lower alkylsulfanyl, lower alkylsulfenyl, lower alkylsulfonyl, oxo, hydroxy, mercapto, amino optionally substituted by alkyl, carboxy, carbamoyl optionally substituted by alkyl, aminosulfonyl optionally substituted by alkyl, nitro, cyano, halogen, or lower perfluoroalkyl, multiple degrees of substitution being allowed. Examples of xe2x80x9calkylenexe2x80x9d as used herein include, but are not limited to, methylene, ethylene, and the like.
As used herein, the term xe2x80x9carylxe2x80x9d refers to a five-to seven-membered aromatic ring, or to an optionally substituted benzene ring system, optionally containing one or more nitrogen, oxygen, or sulfur heteroatoms, where N-oxides and sulfur monoxides and sulfur dioxides are permissible substitutions. Such a ring may be fused to one or more five- to seven-membered aromatic rings optionally containing one or more nitrogen, oxygen, or sulfur heteroatoms. Preferred aryl groups include phenyl, biphenyl, 2-naphthyl, 1-naphthyl, phenanthryl, 1-anthracenyl, pyridyl, furyl, furanyl, thiophenyl, indolyl, isothiazolyl, imidazolyl, benzimidazolyl, tetrazolyl, pyrazinyl, pyrimidyl, quinolyl, isoquinolyl, benzofuryl, isobenzofuryl, benzothienyl, benzindoyl, pyrazolyl, isoindolyl, purinyl, carbazolyl, isoxazolyl, thiazolyl, oxazolyl, benzothiazolyl, benzoxazolyl, and the like. In this regard, especially preferred aryl groups include phenyl, 2-naphthyl, 1-naphthyl, biphenyl, and like ring systems optionally substituted by tert-butyloxy, benzyloxy, n-butyloxy, ispropyloxy, and phenoxy.
As used herein, the term xe2x80x9coptionallyxe2x80x9d means that the subsequently described event(s) may or may not occur, and includes both event(s) which occur and events that do not occur.
As used herein, the term xe2x80x9csubstitutedxe2x80x9d refers to substitution with the named substituent or substituents, multiple degrees of substitution being allowed unless otherwise stated.
As used herein, the chemical structure terms xe2x80x9ccontainxe2x80x9d or xe2x80x9ccontainingxe2x80x9d refer to in-line substitutions at any position along the above defined substituent at one or more of any of O, S, SO, SO2, N, or N-alkyl, including, for example, xe2x80x94CH2xe2x80x94Oxe2x80x94CH2xe2x80x94, xe2x80x94CH2xe2x80x94SO2xe2x80x94CH2xe2x80x94, xe2x80x94CH2xe2x80x94NHxe2x80x94CH3 and so forth.
As used herein, the term xe2x80x9csolvatexe2x80x9d is a complex of variable stoichiometry formed by a solute (in this invention, a compound of Formula (I)) and a solvent. Such solvents for the purpose of the invention may not interfere with the biological activity of the solute. Solvents may be, by way of example, water, ethanol, or acetic acid.
As used herein, the term xe2x80x9cbiohydrolyzable esterxe2x80x9d is an ester of a drug substance (in this invention, a compound of formula (I)) which either a) does not interfere with the biological activity of the parent substance but confers on that substance advantageous properties in vivo such as duration of action, onset of action, and the like, or b) is biologically inactive but is readily converted in vivo by the subject to the biologically active principle. The advantage is that, for example, the biohydrolyzable ester is orally absorbed from the gut and is transformed to (I) in plasma. Many examples of such are known in the art and include by way of example lower alkyl esters (e.g., C1-C4), lower acyloxyalkyl esters, lower alkoxyacyloxyalkyl esters, alkoxyacyloxy esters, alkyl acylamino alkyl esters, and choline esters.
As used herein, the term xe2x80x9cbiohydrolyzable amidexe2x80x9d is an amide of a drug substance (in this invention, a compound of general formula (I)) which either a) does not interfere with the biological activity of the parent substance but confers on that substance advantageous properties in vivo such as duration of action, onset of action, and the like, or b) is biologically inactive but is readily converted in vivo by the subject to the biologically active principle. The advantage is that, for example, the biohydrolyzable amide is orally absorbed from the gut and is transformed to (I) in plasma. Many examples of such are known in the art and include by way of example lower alkyl amides, xcex1-amino acid amides, alkoxyacyl amides, and alkylaminoalkylcarbonyl amides.
As used herein, the term xe2x80x9cprodrugxe2x80x9d includes biohydrolyzable amides and biohydrolyzable esters and also encompasses a) compounds in which the biohydrolyzable functionality in such a prodrug is encompassed in the compound of formula (I): for example, the lactam formed by a carboxylic group in R2 and an amine in R4, and b) compounds which may be oxidized or reduced biologically at a given functional group to yield drug substances of formula (I). Examples of these functional groups include, but are not limited to, 1,4-dihydropyridine, N-alkylcarbonyl-1,4-dihydropyridine, 1,4-cyclohexadiene, tert-butyl, and the like. The term xe2x80x9cpharmacologically effective amountxe2x80x9d shall mean that amount of a drug or pharmaceutical agent that will elicit the biological or medical response of a tissue, animal or human that is being sought by a researcher or clinician. This amount can be a therapeutically effective amount.
Whenever the terms xe2x80x9calkylxe2x80x9d or xe2x80x9carylxe2x80x9d or either of their prefix roots appear in a name of a substituent (e.g. arylalkoxyaryloxy) they shall be interpreted as including those limitations given above for xe2x80x9calkylxe2x80x9d and xe2x80x9carylxe2x80x9d. Alkyl substituents shall be recognized as being functionally equivalent to those having one or more degrees of unsaturation. Designated numbers of carbon atoms (e.g. C1-6) shall refer independently to the number of carbon atoms in an alkyl moiety or to the alkyl portion of a larger substituent in which the term xe2x80x9calkylxe2x80x9d appears as its prefix root. Similarly, the term xe2x80x9cC2-C8 alkenylxe2x80x9d and C2-C8 alkynylxe2x80x9d refer to groups having from 2 to 8 carbon atoms and at least one carbonxe2x80x94carbon double bond or carbonxe2x80x94carbon triple bond, respectively. The term xe2x80x9clowerxe2x80x9d, for example in relation to xe2x80x9clower alkylxe2x80x9d refers to a C1-6 alkyl group.
As used herein, the term xe2x80x9coxoxe2x80x9d shall refer to the substituent xe2x95x90O.
As used herein, the term xe2x80x9chalogenxe2x80x9d or xe2x80x9chaloxe2x80x9d shall include iodine, bromine, chlorine and fluorine.
As used herein, the term xe2x80x9cmercaptoxe2x80x9d shall refer to the substituent xe2x80x94SH.
As used herein, the term xe2x80x9ccarboxyxe2x80x9d shall refer to the substituent xe2x80x94COOH.
As used herein, the term xe2x80x9ccyanoxe2x80x9d shall refer to the substituent xe2x80x94CN.
As used herein, the term xe2x80x9caminosulfonylxe2x80x9d shall refer to the substituent xe2x80x94SO2NH2.
As used herein, the term xe2x80x9ccarbamoylxe2x80x9d shall refer to the substituent xe2x80x94C(O)NH2.
The present invention also provides a method for the synthesis of compounds useful as intermediates in the preparation of compounds of Formula (I) along with methods for the preparation of compounds of Formula (I).
A suitably protected alpha-amino acid (1), where PG is an amine protecting group such as tert-butoxycarbonyl, is treated with an amine in the presence of a coupling reagent such as but not limited to diisopropyl carbodiimide (DIC) to form the amide (2). The xcex1-amino group in (2) is then deprotected, employing a strong acid such as hydrogen chloride for the case where PG is tert-butoxycarbonyl, to afford the free amine (3) either as the free base or as a salt (Scheme 1). A suitably protected alpha-amino acid (1), where PG is an amine protecting group such as tert-butoxycarbonyl, is treated with an amine in the presence of a coupling reagent such as but not limited to diisopropyl carbodiimide (DIC) to form the amide (2). The xcex1-amino group in (2) is then deprotected, employing a strong acid such as hydrogen chloride for the case where PG is tert-butoxycarbonyl, to afford the free amine (3) either as the free base or as a salt (Scheme 1). 
To further derivatize the amino group of compound (3), the free amino compound, or the suitable salt thereof may be treated with an aldehyde or ketone R12C(O)R11 in the presence of a reducing agent such as sodium cyanoborohydride or sodium triacetoxyborohydride to afford compound (4), where R12 and R11 are defined such that R2 in (4) conforms to the specifications for Formula (I). Alternately, the amine compound (3) may be treated with tertiary amine base such as DIEA and a molar equvalent amount (or slight excess) of an alkylating agent of general structure R2xe2x80x94Z, where Z is a nucleofugal group such as bromine, to form the secondary amine compound (4) (Scheme 2). Amine (3) may be treated with a tertiary amine base such as DIEA and 2 molar equivalents (or slight excess) of an alkylating agent of general structure R2xe2x80x94Z, where Z is a nucleofugal group such as bromine, to form the amine compound (5). Alternately, the amine compound (3) may be treated with an electron deficient olefinic compound such as but not limited to ethyl acrylate, to afford the adduct intermediate (6). Compound (6) may be manipulated, employing methods known in the art such as hydride reduction, in transforming such an adduct to compounds of general structure (4). 
To further derivatize the amino group of compound (3), the free amino compound, or the suitable salt thereof may be treated with a sulfonyl chloride such as benzenesulfonyl chloride to form the sulfonamide (7) (Scheme 3), where R14 is C1-6 alkyl, C1-6 alkylaryl, or aryl. Alternately, an amine R15xe2x80x94NH2 may be treated with sulfuryl chloride and the intermediate then treated with (2) to afford the sulfonylurea (7) where R14 is xe2x80x94NHxe2x80x94C1-6 alkyl or xe2x80x94NHxe2x80x94C1-6 alkylaryl. 
To further derivatize the amino group of compound (3), the free amino compound, or the suitable salt thereof may be treated with an isocyanate R15NCO in the presence or absence of a tertiary amine base such as TEA to form the urea (8) (Scheme 4), where R15 is xe2x80x94C1-6 alkyl or xe2x80x94C1-6 alkylaryl and Q is NH. Alternately, compound (3) may be treated with R15Oxe2x80x94C(O)Cl and a tertiary amine base such as TEA to afford compound (8) where R15 is xe2x80x94C1-6 alkyl or xe2x80x94C1-6 alkylaryl and Q is O. 
Compound (9) may be treated with triphenyl phosphine, either diisopropyl azodicarboxylate (DIAD) or diethyl azodicarboxylate (DEAD) and an alcohol R16xe2x80x94OH to form the compound (10) (Scheme 5), after removal of the protecting group PG. R16 is xe2x80x94C1-6 alkyl, xe2x80x94C1-6 alkylaryl, xe2x80x94C1-6 alkyl-OSi(C1-6 alkyl)3, xe2x80x94C1-6 alkyl-OSi(C1-6 alkylaryl)3, or xe2x80x94C1-6 alkyl-NR8R9 (provided that neither R8 nor R9 are hydrogen). PG may be, for example, tert-butoxycarbonyl, benzyloxycarbonyl, and the like. 
Compound (3) or a suitable salt thereof may be treated with a acid anhydride (R17xe2x80x94CO)2O and a base such as TEA in the presence or absence of pyridine or DMAP to afford compound (11) (Scheme 6). The substituent R17 may be chosen such that the group R17xe2x80x94C(O)xe2x80x94 is as specified for R2 in Formula (I). Alternately, compound (3) may be treated with the acid chloride R17xe2x80x94COCl and an tertiary amine base such as TEA in the presence or absence of pyridine or DMAP to afford compound (11). Alternately, compound (3) may be treated with the carboxylic acid R17xe2x80x94CO2H and a carbodiimide reagent (i.e., a xe2x80x9ccoupling reagentxe2x80x9d) such as EDC, DIC, or DCC in the presence or absence of HOBt to provide compound (11). 
Compound (3) or a suitable salt thereof may be treated (Scheme 7) with an activated amidine reagent such as N,Nxe2x80x2-bis-BOC-1-guanylpyrazole or 3,5-dimethylpyrazole-1-carboxamidine nitrate in the presence of a tertiary organic base such as TEA to generate the guanidine compound. Guanidine substituent protecting groups may be removed. For example, where N,Nxe2x80x2-bis-BOC-1-guanylpyrazole is employed, the BOC groups of the adduct may be removed with a strong acid such as hydrogen chloride to afford the free guanidine compound (12), where R5 and R6 are as defined for Formula (I). 
General Experimental
LC-MS data was obtained using gradient elution on a Waters 600 controller equipped with a 2487 dual wavelength detector and a Leap Technologies HTS PAL Autosampler using an YMC Combiscreen ODS-A 50xc3x974.6 mm column. A three minute gradient was run from 25% B (97.5% acetonitrile, 2.5% water, 0.05% TFA) and 75% A (97.5% water, 2.5% acetonitrile, 0.05% TFA) to 100% B. The MS was a Micromass ZMD instrument. All data was obtained in the positive mode unless otherwise noted. 1H NMR data was obtained on a Varian 300 MHz spectrometer.
Abbreviations used in the Examples are as follows:
APCI=atmospheric pressure chemical ionization
BOC=tert-butoxycarbonyl
BOP=(1-benzotriazolyloxy)tris(dimethylamino)phosphonium hexafluorophosphate
d=day
DIAD=diisopropyl azodicarboxylate
DCC=dicyclohexylcarbodiimide
DCM=dichloromethane
DIEA=diisopropylethylamine
DMF=N,N-dimethylformamide
DMPU=1,3-dimethypropylene urea
DMSO=dimethylsulfoxide
EDC=1-ethyl-3-(3-dimethylaminopropyl)-carbodiimide hydrochloride
EDTA=ethylenediamine tetraacetic acid
ELISA=enzyme-linked immunosorbent assay
ESI=electrospray ionization
ether=diethyl ether
EtOAc=ethyl acetate
FBS=fetal bovine serum
g=gram
h=hour
HBTU=O-benzotriazol-1-yl-N,N,Nxe2x80x2,Nxe2x80x2-tetramethyluronium hexafluorophosphate
HMPA=hexamethylphosphoric triamide
HOBt=1-hydroxybenzotriazole
Hz=hertz
i.v.=intravenous
kD=kiloDalton
L=liter
LAH=lithium aluminum hydride
LDA=lithium diisopropylamide
LPS=lipopolysaccharide
M=molar
m/z=mass to charge ratio
mbar=millibar
MeOH=methanol
mg=milligram
min=minute
mL=milliliter
mM=millimolar
mmol=millimole
mol=mole
mp=melting point
MS=mass spectrometry
N=normal
NMM=N-methylmorpholine, 4-methylmorpholine
NMR=nuclear magnetic resonance spectroscopy
p.o.=per oral
PBS=phosphate buffered saline solution
PMA=phorbol myristate acetate
ppm=parts per million
psi=pounds per square inch
Rf=relative TLC mobility
rt=room temperature
s.c.=subcutaneous
SPA=scintillation proximity assay
TEA=triethylamine
TFA=trifluoroacetic acid
THF=tetrahydrofuran
THP=tetrahydropyranyl
TLC=thin layer chromatography
Tr=retention time
The following compounds are synthesized according to the Schemes.